This invention relates to a photographic recording material and, more particularly, to a photographic recording process for forming a metal-chelated dye within an image-receiving layer using a dye ligand or a dye ligand-forming substance capable of forming a metal chelate, which process comprises fixedly incorporating a metal in the image-receiving layer of the photographic recording material.
The use of a dye or a dye-forming substance in a photographic recording material, and in particular in a diffusion transfer process photographic recording material is known. With such photographic materials, stability of the formed dye image, particularly, resistance to light, is one of the serious subjects. The use of a metal-chelatable dye for improving resistance of the dye image to light is also known. Examples of using metal-chelatable dyes are described in, for example, U.S. Pat. No. 3,196,014. In diffusion transfer process photography, the diffusing speed of the metal-chelatable dye becomes very slow due to the huge molecular weight of the metal-chelated dye. Accordingly, the appearance of an image after imagewise exposure and development processing is often delayed. Therefore, formation of the complete image requires a substantially long period of time. In order to remove such disadvantage, U.S. Pat. No. 4,239,847 discloses a process for forming a metal-chelated dye by immobilizing a metal within an image-receiving layer with a polymer ligand. The process uses an unchelated, chelatable dye ligand or dye ligand-forming substance, and causes a ligand exchange reaction between the metal complex of the polymer ligand and the dye ligand within the image-receiving layer. However, the use of a chelatable polymer ligand for immobilizing metal causes a change in viscosity of a coating solution of the polymer-containing layer depending upon the viscosity of the polymer. Therefore, it becomes difficult to obtain a photographic recording material having an accurate and uniform film thickness. Furthermore, when using a cationic polymer as a mordant and an anionic polymer as a polymer ligand, an insoluble polyion complex is produced to form agglomerates (called seeding) inconvenient for obtaining smooth coating. Therefore, they cannot be coated as one layer. In order to avoid this seeding, it has been proposed to coat the cationic polymer mordant and the polymer ligand as different layers. In this case, a polyion complex is still formed at the interface between the two layers to cause visual turbidity (called haze). Accordingly, the commercial value of the material is deteriorated. In addition, providing different layers increases the distance between the dye ligand or dye ligand-forming substance-containing layer and the mordant layer for immobilizing imagewise released dye. This prolongs the time necessary for the completion of image after imagewise exposure and development processing, thus seriously deteriorating the commercial value of the photographic recording material because products capable of providing an image in as short a time as possible are demanded.
Examples of processes for producing the polymer ligands include a process involving the reaction between a polymer having a reactive group and a low molecular compound having a coordinating group (so-called high molecular reaction) as described in U.S. Pat. No. 4,239,847, Functional Polymers, compiled by Kobunshi Gakkai and published by Koritsu Shuppan, p. 34-36 (Tokyo, 1974), and a process involving synthesizing a monomer having a coordinating group, and polymerizing the resulting monomer (so-called monomer process) as described in U.S. Pat. No. 4,239,847, Functional Polymers cited above p. 36-38.
In the former high molecular reaction, reactivity is generally less than that in reactions between low molecular compounds. Therefore, the ratio of introducing coordinating groups into the high polymers is so low that only a polymer ligand with poor quality is obtained.
In the latter monomer process, the monomer has a polymerizable group due to its essential properties. During the reaction step of introducing a coordinating group into the monomer, undesirable reactions of the polymerizable group often take place. This causes difficulties in the reaction procedure such as damaging a reactor, deterioration of washability of a reactor. These difficulties result in reducing the yield of the monomer having a coordinating group, resulting in deterioration of productivity and economical properties.
In the process of producing a metal-chelated dye within an image-receiving layer using a previously non-chelated dye ligand or dye ligand-forming substance, a metal ion coated as an image-receiving layer tends to diffuse into other layers. When it reaches a light-sensitive emulsion layer, it creates harmful photographic properties. Even when it does not reach a light-sensitive emulsion layer, dispersion of the metal ion in several layers between a mordant layer and a light-sensitive emulsion layer leads to formation of a metal-chelated dye before a dye ligand released by imagewise exposure and subsequent development reaches the mordant layer. This results in an undesirable increase in image-transferring time or a reduction in image density. In order to prevent this harmful function, the metal ion must be securely immobilized in a specific layer within an image-receiving layer. However, when a dye ligand is released by imagewise exposure and subsequent development and reaches the image-receiving layer, the immobilized metal ion must react with the dye ligand to cause a ligand exchange reaction.